The invention relates to a device for monitoring the storage level of a product contained in a tank. More particularly, it lies in the field of the distribution of bulk products such as industrial gases, petrol, etc. which are stored in tanks or appropriate storage facilities, installed on industrial sites at customers"" premises close to the installations which consume these products.
Tanks are known which are equipped with a device for monitoring product storage level comprising a sensor for measuring the quantity of product contained in the tank and an associated controller for utilization thereof. The controller continuously scrutinizes the storage level of the tank output by the sensor and, depending on a preset threshold, transmits a restocking command, for example via a telephone network, to a centre of a supplier responsible for stocking the tank. Additionally, the known device is furnished with a digital or analog display controlled by the controller so that the customer can at any moment ascertain the quantity of product remaining in the tank.
This known device has the drawback that only the storage level of the product is displayed. Consequently, the customer has no means of knowing on the one hand whether or not a restocking command has been sent and, on the other hand, should it have been sent, whether this command has been recorded by the supplier. Therefore, the customer is in a state of uncertainty and must himself check whether the storage level has dropped below the preset threshold, this requiring regular intervention on his part. Once he has noted that the threshold has been crossed, he is compelled to contact the supplier so as to request confirmation from the latter that a restocking command for the tank in question has indeed been recorded. Moreover, before he has contacted the supplier, he does not know the day on which the latter will call. This is why he must at all times be ready to make the necessary arrangements for the filling of the tank in question, such as, for example, shutting down the installations which are fed from it. Out of concern for quality of service on the part of the supplier, this onus of customer-side checking is undesirable.
Additionally, in the case of the known devices which display only the storage level, it is sometimes difficult for the customer to perceive certain malfunctions such as, for example, inconsistent measurement values output by a faulty sensor.
The present invention aims to alleviate these various drawbacks by proposing a monitoring device which makes it possible to inform a customer using a product storage tank more fully as to the current state of the tank and as to the state of operation of the device, and especially as to the fact that a restocking command has indeed been recorded at the restocking centre without the user having to do anything to, for example, contact his supplier.
To this end, the subject of the invention is a device for monitoring the storage level of a product contained in a tank, comprising means for measuring the storage level of the product, a central processing unit for utilizing the level read off by the measurement means, memory means for holding at least one storage level threshold, means for comparing a level value output by the central processing unit with the said threshold, means for triggering a restocking command and controlled by the comparison means, and means for transmitting the restocking command to a restocking centre, characterized in that it furthermore comprises means for receiving at least one item of information which is issued by the said restocking centre in response to the transmission of the said restocking command, and in that it comprises a display unit which exhibits an area for displaying the said item of information issued by the restocking centre.
The device according to the invention may additionally comprise one or more of the following characteristics:
the device comprises means for checking the operation of the central processing unit, and the display unit comprises an area for displaying the state of operation of the central processing unit,
the device comprises means for checking the operation of the means for measuring the storage level of the product, and the display unit comprises an area for displaying the state of operation of the measurement means,
the device comprises means for checking the operation of the transmission and reception means, and the display unit comprises an area for displaying the state of operation of the transmission and reception means,
the device comprises means for calibrating the means for measuring the storage level and means for checking the operation of the calibration means, and the display unit comprises an area for displaying the state of operation of the calibration means,
the device comprises a back-up electrical power supply unit, means for checking the operation of the back-up electrical power supply, and the display unit comprises an area for displaying the state of operation of the electrical power supply unit,
the display unit comprises at least two areas for displaying the storage level of the product, one of which is of the type with incremental display and the other of the type with digital displayxe2x80x94the display unit comprises a liquid crystal display.
The subject of the invention is also a tank comprising a monitoring device of the type defined above.